Terpene separation



Patented Jan. 29, 1946 2,393,894 TERPENE SEPARATION Nicholas T. Farinacci, Wilmington, and William J. Kirkpatrick, Marshallton, Del., assignors to Hercules Powder Company, Wilmington, Del :1.

corporation of Delaware No Drawing. Application April 24, 1943 Serial No. 484,474

10 Claims. (01. 260--ii75.5)

This invention relates to a process for the separation of camphene from a terpene mixture, and particularly to the separation of pinene from camphene.

isomerization of pinene to camphene.

methods of distillation.

means of distillation.-

ture.

ing the reflux condenser.

I filtered out.

was cooled and-separated into 1ayers.

layer was washed free of sodium hydroxide with water. It was then subjected to steam distillation, 95 to 97% being volatile with steam. The other, 3 to 5% was polymer. The steam volatile portion wa analyzed by a combination of frac- The chemical literature is extensive on the 5 tional distillation, bromination, and catalytic hy- Many drogenation giving the following composition of methods have been disclosed showing a one-step the mixture? catalytic conversion of pinene to camphene, but Per cent none of these methods are capable of a 100% con- Pi e e version, few are capable of a conversion of more C mp ene 69 than 0%, and most are capable of a conversion of Menthadiene 13 less than 50%. In every case, the resulting mix- D-Cymene, p-menthene, and p-menthane 16.6 ture after isomerization contains a considerable The terpene mixture d in example was percentage of meaeted pmene' when is f prepared by means of the isomerization of alphaslrable 9 obtain substantially pure eamphene' 15 pinene using vermiculite as the catalyst and caris pmetlcany impossible to separate ried out under conditions controlled in such a acted pmene from the eamphene by ordinary manner as to cause 93% of the pinene to be converted to camphene and para-menthadienes, leav- Now, in accordance with the present invention, ing about 7% unchanged pmerm However, any it e been discovered that eamphene may be starting material containing camphene and at feetlvely emeienfly, and eemomlcau? separated least one oth'er terpene isomerizable under the 1mm e terpene having a fling conditions of this invention may be used. point relatively close to the boiling point of cam- Separation of camphene fr terpene mixtures phene by heating the terpene mixt above may be made in accordance with theconditions bemng point the presence catalyst having of isomerization shown here when the camphene alkaline reaction e separating the is present in amounts from about 5 to about 95% ponents m the resultmg mixture by ordinary of the total amount of terpenes present in the mixture to be se arated. p A method of carrying out the process of this ine present g m of camph'ene separation is vention is illustrated by the following specific exparticularly applicable to terpene mixtures com ample; which is not to be consirued as limiting taining a preponderance of camphene as, for exm when the parts expressed are by weight: ample, terpene mixtures resulting from the isom- Example erization of pinene using such ni'xinerailtype catalysts-as, for example, vermiculte, jul ers earth, one hundred Parts of freshly dlstmed Floridin (dried Florida earth),Japanese acid clay, menial P i m the trade as kaolin alumina, silica, silicates of lime and alu- Hercule? Pmene In) contaming about mina kieselguhr red phosphorous phosphate of alphaplilene were heated to the reflux tempelia' alumina, charceal, montmorilloriite, aiuminoparts of heatiexpa'ndefl vermiculite silicic acids etc. Other catalysts are those of the (zonohte) i aidded rapldly but small 40 inorganic 'type as, for example, metaboric acid. Ega gg ggf xg ai g 2, 33: gifig 2 3? pyro-bor'ic acid, silica gel that hasbeen surface vision was made for removing any 'water'reacm activated, titanic acid,silicic acid, triphosphoric About 93 95% of the acid, penta-phosphoric acid, vanadic acid, antipinene had (heed isomerized m the first to 10 5 monic acid, phosphotungstic acid, silico-tungstic minutes of reaction time. After this time, the 1 acid- Further catalysts are the reaction mixture was cooled and.the "catalyst type e oxalic acid acetic aeld' valerianic acid, butyric acid, palmitic acid, hen: This filtered reaction mixture was then charged acid Phthalic d intoasilver-lined pressure vessel with equalparts 9m 0! these catalysts are powerful that by volume of ,33 aqueous sodium hydroxide the camphene itself is used up, in some casesgo- The mixture was heated for 2 hours at 260 C. ing to polymers, in other cases to para-menthene, under vigorous agitation. The reaction mixture para-mentliane, and para-cymene; Some'of-the The oil other catalystsare so feeble that they cause only a low conversion of pinene to camphene. Regardexample,

less of the type oi catalyst used, there is always present in the resulting mixture some percentage of unchanged pinene. Thepresence of this pinene causes a low apparent yield of camphene because and terpinolene, which are not obtained as a product in accordance with this alkaline-isomerization reaction. Other by-products produced and which may be efliciently, effectively, and economically separated from camphene by means of ordinary distillation methods ar allo-ocimene and para-cymene. Some camphene is also produced, thereby increasing the sum total yields of camphene desired.

The process of the-present invention may be carried out by heating the mixture of terpenes including isomerizable terpenes and camphene to a temperature between about 200 C. and. about 300 C. or at about the boiling point of the terpene mixture and preferably at a temperature between about 240 C. and about 270 C.

The time required for substantially complete conversion of the undesirable pinene component present in a terpene mixture containing a pretion in a concentration of between about 0.5% and about 5%.

All of the alkaline catalysts oi the general types herein disclosed are suitable for isomerizing alpha-pinene to dipentene free of alpha-- terpinene. However, in addition to dipentene there is obtained more or less allo-ocimene as a by-product depending on the catalyst being used. This allo-ocimene may be obtained as a Inert solvents such .as alcohols as well as water K may be used.,as solvents for the catalyst. Suitponderance of camphene varies in accordance with the temperature at which the isomerization is carried out. The rate of conversion of thepinene to monocyclic terpenes particularly rich in=dipentene is relatively slow at a temper! ature below the boiling point of the terpene mixture and the rate of conversion increases considerably as the temperature-isincreased approaching as an upper limit about 300 C. Maximum conversion rates are obtained between about 240 C. and about 270 C.

The alkaline catalysts or catalysts having an alkaline reaction found suitable in accordance with this invention are alkali metal and alkaline earthinetal water-soluble hydroxides, carbonates, sulfites, phosphates, silicates and salts of weak acids which hydrolyze readily to give basic solutions under the conditions of temperature and pressure at which the process of this invention is carried out. Catalysts having an alkaline reaction which are especially desirable in carrying out the process of this invention are potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium silicate, trisodium phosphate, sodium hexa-meta-phosphate, sodium suliite, sodiumsilicate, potassium sulflte, cesium hydroxide, rubidium hydroxide, etc. Other alkaline catalysts suitable. for the p poses of this invention are the organic bases as, for tetramethyl ammonium hydroxide, guanidinium hydroxide, piperidinium hydroxide, ammonium hydroxide, triethanolamine, diamylamine, triamylamine, aniline, etc.

The ratio of the alkali catalysts may vary within wide limits, depending upon the particular catalyst being used. When potassium or sodium hydroxide is used 'as the catalyst, it is preferred able alcohols are methyl alcohol, ethyl alcohol,

propyl alcohol, isopropyl alcohol, butyl alcohol,-

dihydric alcohols as, for example, ethylene glycol, diethylene glycol, propylene glycol, and trihydric alcohols such as glycerol and trimethanol menthane.

The process may be carried out continuously by passing the mixture of alpha-pinene or other terpenes capable of being isomerized under the conditions of this invention together with camphene in the presence of an alkaline catalyst through suitable tubes or other chambers maintained at a temperature above the boiling point vious that a new process has been provided for the separation of camphene from a terpene mixture including'isomerizable terpenes which comprises heating the terpene mixture above its boiling point in the presence of a catalyst having an alkaline reaction and then subjecting the remethods of distillaterpene mixture comprising camphene and pinene, said process comprising converting the pinene content of the terpene mixture to dipentene by heating said terpene mixture at a temperature between about 200 C. and about 300 C. in the presence of a dissolved catalyst having an alkaline reaction, and separating the camphene from the catalyst-treated terpene mixture comprising camphene and dipentene by distillation.

2. A process of separating camphene from a terpene mixture comprising camphene and pinene, said process comprising converting the. pinene content of the terpene mixture to dipentene by heating said terpene mixture at a temperature between about 200 C. and about 300 C. in the presence of a dissolved organic base catalyst. and separating the camphene from the catalysttreated terpene mixture comprising camphene and dipentene by distillation.

3.'A process of separating camphene from a terpene mixture comprising camphenev and pinene, said process comprising converting the pinene content of the terpene mixture to dipentene by heating said terpene mixture at a to use these catalysts in aqueous or alcoholic solu- :5 temperature between about 200 C. and about v terpene pinene, said process comprising converting the 300 C. in the presenceyoi adissolved inorganic base catalyst, and separating the camphene from the catalyst-treated terpene mixture comprising camphene and dipentene by distillation.-

4. A process of separating camphene from a terpene mixture comprising camphene and pinene, said process comprising converting the pinene content of the terpene mixture to dipentene by heating said terpene mixture at 'a temperature between about 200 C. 'and about 300 C. in the presence of dissolved sodium hydroxide, and separating the camphene from the sodium hydroxide-treated terpene mixture comprising camphene and dipentene by distillation.

a 5. A process of separating camphene from a pinene content of the terpene mixture to dipentene by heating said terpene mixture at a temperature between about 200 C. and about 300 C. in the presence of aqueous sodium mixture comprising "camphene andpinene, said process comprising converting the.

pinene content of the terpene mixture to dipentene by heating said terpene mixture at a temperature between about 200 C.. and about 300 C. in the presence of dissolved diamylamine, and separating the camphene from the diamy'lamine-treated terpene mixture comprising-calm phene and dipentene by distillation.

.8. A process of separating camphene irom a terpene mixture comprising camphene and pinene, said process comprising converting the pinene content of the terpene mixture to dihydroxide, and separating the camphene from .pentene bylheating said terpene mixture at a temperature between about 240 C. and.about 270 C; in the presence of a dissolved catalyst having analkaline reaction, and separating the camphene from the catalyst-treated terpene mixture comprising camphene and dipentene by distillation.

9. A process of separating camphene from pinene comprising converting the pinene content ofa camphene-pinene mixture to dipentene by heating said mixture at a temperature between about200 C. and about. 300' C. in--.the presence oi a dissolved catalyst having an alkaline reaction, and separating the camphene from the dipentene by distillation.

10. A process of separating camphene irom pinene comprising converting the pinene content of a camphene-pinene mixture to dipentene by heating said mixture at a temperature between about 200 C. and about 300 C. in the presence or dissolved sodium hydroxide, and separating the camphene from the dipentene by distillation.

mcnoms 'r.- FARINACCI. wrnuau- J. .mRKPATRICK. 

